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Sending Successful Email Survey Invites

October 7, 2021

How Researchers Can Navigate the Landscape of Sending Invites and Communication to Survey Respondents

An important aspect of data collection in the insights industry is the ability to get survey invites out to potential respondents and recruit them for research projects. In the past this was a fairly simple undertaking – set up an email invite and blast it out to your client’s respondent list, and then let the responses pour into your survey. However, with increasing concerns regarding security and unwanted spam messages, this once simple task has become a much more complex process. At Big Village Insights, we have engaged thought leaders within our business and around the industry to develop a process to assure our invites make it to respondents’ inboxes so we can capture the insights needed by our clients. As researchers attempt to navigate this constantly changing situation, there are several easy things you can all do to improve response rates on research projects.

When Should You Send Your Emails?

There are a great number of opinions around when is the best time to send messages over the course of the day. While research does show a slightly higher response rate when messages are sent on a Tuesday, the difference between sending Tuesday and sending any other weekday is minimal. It is best to avoid weekends when folks are generally paying less attention to their email. If you are sending messages to respondents around the globe, schedule messages to send to respondents during their daytime hours. This practice improves your standing with respondent spam filters.

Subject Lines – Do’s and Don’ts

A poorly written subject line can wreck your chances of getting a respondent to give attention to your survey invite. There are some basic guidelines in this area:

  • Avoid all capital letters – Capital letters can be perceived as yelling at your respondents.
  • Avoid exclamation points (!) – When was the last time you opened an email with a bunch of exclamation marks in the subject?
  • Avoid mention of an incentive in the subject line – We frequently offer incentives to participate in our research and while it might be tempting to call attention to what the respondent will get for participating in your research, it should be avoided. You may accidentally trigger spam filters to look at your invite as some sort of promotion and miss out on your respondent’s inbox. It’s best to leave incentive mentions for the body of the email.
  • Call attention to relationships between respondent and clients – Remember, these respondents have some sort of relationship with your end client, and wherever possible, calling attention to that relationship with your respondent will help get their attention. “Brand X would like to get your feedback on a new offering you recently tried” is an example of a simple call-to-action subject line that informs the respondent what we want them to do and why they are receiving the message.

Can I Send All My Invites Out at Once?

This depends on how much the email address from which you’re sending is utilized. The email address from which you are sending invites is often referred to as your domain. The strength of your domain’s reputation is very important to email service providers (ESPs) and will govern what ESPs decide to do with your message. The nature of our business makes this piece of the process tricky. To maintain a strong domain reputation, it’s important for ESPs to see your domain on a consistent basis so they know who you are and know they can trust you. Ideally, that means sending roughly the same number of invites each day, so your domain’s reputation stays “warm” with the ESPs. Again, in an ideal environment, it doesn’t matter if you send five hundred emails a day or five million emails a day. Sending them consistently maintains your reputation with ESPs and gets your messages in respondents’ inboxes. In our industry, the need to send survey invites is likely to eb and flow with your clients’ needs. It’s important to warm your domain slowly to avoid causing the ESPs to get alarmed. If you’ve been sending messages at a rate of about five hundred a day, and a project comes along with five million invites, slowly ramp up your email sends over several days. If ESPs are used to seeing five hundred messages from you a day and suddenly get millions of invites, that will draw a red flag. Be aware of how much mail volume is being sent out from your domain and ramp up your sends by roughly doubling the number of messages you send each day until you reach the number you need to send to meet the needs of a large project.

What About the Message Itself?

To comply with legal requirements on sending emails, many countries enforce that your message includes a link to your organization’s privacy policy along with an easy way to unsubscribe from messages if the respondent chooses. Consider putting the unsubscribe link at the top of your message. This may seem illogical by giving respondents a quick and easy out, however, by making it super easy to unsubscribe, you make it less likely they will complain about your message to their ESP. ESPs have a very low tolerance for complaints and will quickly take steps to block your messages if they get complaints from even a small percentage of their users.

While logos from your end client or small images can liven up your email message, there are two important things to remember when including images:

  • Too many images or an email mostly made up of images can trigger spam filters. An old trick spammers would use was to send emails as images to avoid spam filters from being able to scan message content. ESPs have become wise to this practice and your chances of being viewed as spam go up if you’re message is more than half images.
  • Some ESPs will not download images within messages by default. The user must click on a link to allow the images to be downloaded. Therefore, while using a few images is ok, it’s a good idea to make sure your message looks fine if the images do not download and the respondent sees your invite with just the text.

What If I Do Get into Trouble?

In many cases, the first sign of trouble on an email campaign is that your response rate is much lower than you’d expected. This alone does not always mean your domain is in trouble, however, if you see issues across more than one project, a domain problem might be the root cause. Sadly, there are no quick fixes to domain problems and vigilance as suggested earlier is the best defense. There are many domain health monitoring tools available such as MX Toolbox that your Information Technology (IT) team can monitor to watch out for warning signs such as your domain being on a common black list/disallow list. Regular monitoring helps detect early signs of trouble. Having a few backup domains on hand to spin up is also helpful. If you do choose to spin up a backup domain, you will need to send emails slowly at first and then ramp up. Maintaining multiple domain sending volumes can be challenging for smaller organizations, but if you have the capabilities to manage them, it is recommended. That way, when there is a situation needing to shift work off a troublesome domain, you can do so quickly and efficiently. If you do get into trouble, don’t panic and rush to shift domains. Take the time to spin up a new domain properly and remedy any issues your IT team identifies. Trying to fix these types of problems quickly almost always leads to additional trouble for your organization.

A Few Technical Notes on Email Deliverability

A major red flag to an ESP is seeing a lot of undeliverable/bounce back email traffic from a domain. If you look at it from the perspective of the ESP, while occasional mistakes in typing email addresses can cause a bounce back, one thing they can count on is that all legitimate messages coming into their system are able to be delivered to one of their users. ESPs are therefore naturally more suspicious of a domain sending them a lot of undeliverable messages. In the Insights industry, we are often sending messages on behalf of our clients. To maintain our domain reputation as well as protect our clients, it is important to use an email verification service when sending messages. There are several services that will meet this need such as Never Bounce, Email List Verify, etc. It is highly recommended that you run your email list through a verification service and that this step is incorporated into your sending procedures. There are costs associated with these services but the benefits they provide to domain reputation makes the costs worth it.

Finally, there are important steps your IT team should take to make sure your domain is set up correctly from a technical perspective. At Big Village Insights, we adhere to industry-standard practices in bulk emails by utilizing SPF, DKIM, and DMARC, which verify us as legitimate email senders.

In Summary

Sending email campaigns continues to become more complicated and require a greater degree of care to be successful. Always ask yourself very honestly, “If I saw this message in my inbox, would I bother to open it? Read it? Participate in the survey?” Ask yourself if the message you are sending quickly and simply communicates why you are contacting this individual and what it is you want them to do. You should mention any incentive being offered, but don’t make that the center point of your message. Again, think about how you’d react if the message was in your inbox. Too much emphasis on the incentive gets people thinking this might be a scam. Remember they have some sort of relationship with your client – call attention to that relationship and why you’re send the message. Don’t get too worried about what day of the week you send your messages, just avoid weekends and sending messages that will be received over night by your respondents. Be careful to watch your bounce back rates and verify your IT team has set up your domain using industry standard practices. Most of us get a lot of email messages each day, and so do our respondents. We have to cut through all the noise to get our respondents’ attention so they can offer us their valuable insights. Following these guidelines will help you achieve that goal.


Written by Tom Spindler, Director, Script Services at Big Village Insights.